509149-27-3Relevant articles and documents
Endo/exo stereoselectivity in Diels-Alder reactions of α,β-Dialkylated conjugated enals to cyclic 1,3-dienes: Intermediates in the synthesis of (-)-β-santalol and its analogs
Chapuis, Christian,Skuy, David,De Saint Laumer, Jean-Yves,Brauchli, Robert
, p. 1470 - 1516 (2015/02/19)
Highly exo-selective [4+2] cycloadditions of cyclopenta-1,3-diene 2a to α,β-dialkyl conjugated enals 5 are compared with the analogous endo-favored Diels-Alder reaction of cyclohexa-1,3-diene 7. The exostereoselectivity is lower in the homologous case of methylcyclopenta-1,3-diene 9. This diastereoselectivity is discussed either in terms of a retro-homo-Diels-Alder reaction, associated with thermodynamic control, or with respect to either a competing hetero-Diels-Alder/Claisen or Cope domino pathway, or retro-Claisen/retro-hetero-Diels-Alder of the endo-homo-cycloadducts. These hypothetical mechanisms have been examined by DFT calculations at the MPW1K(CH2Cl2)/6-31+G? ? level of theory for the AlCl3-mediated cycloadditions of 5d to 2a and 7. Application of Corey's methodology to the g-halogenoa- methyl-substituted dienophiles 5a and 5b allowed an enantioselective preparation of known and useful intermediates for the synthesis of either the naturally occurring (-)-β-santalol or its potentially olfactive structural analogs.
Asymmetric desymmetrization based on an intramolecular haloetherification: A highly effective and recyclable chiral nonracemic auxiliary, 2-exo-methyl-3-endo-phenyl-5-norbornene-2-carboxaldehyde, for meso-1,3- and meso-1,4-diols
Fujioka, Hiromichi,Fujita, Tetsuya,Kotoku, Naoyuki,Ohba, Yusuke,Nagatomi, Yasushi,Hiramatsu, Atsushi,Kita, Yasuyuki
, p. 5386 - 5397 (2007/10/03)
A new chiral auxiliary, a 3-endo-phenyl norbornene aldehyde derivative, which is a crystalline, very stable, and easily handled, was developed for the desymmetrization of meso-1,3- and meso-1,4-diols. The key step of the method, an intramolecular bromoeth
